Did you downloads an STDS then convert to DEM? This tends to be what I
see. My suggestion is to create a TIN, then add the DEM file as part of
that TIN. If you do this, C3D will perform a transformation that it
won't do if you just build direct from TIN. Don't ask me why.
If you happen to own a copy of Mastering, we look at this exact
procedure on Page 123. Hope this helps.
--
James Wedding, P.E.
Engineered Efficiency, Inc.
The Site: www.eng-eff.com
The Blog: www.civil3d.com
The Book: www.masteringcivil3d.com
Mac Book Pro C3D SP2, XP SP2, 2GB